'''函数变量'''

def add(a,b):
    return a+b

def mul(a,b):
    return a-b

def get_obj(s):
    if s == '+':
        return add
    if s == '-':
        return mul

def main():
    s = input("请输入计算式，仅限加键")
    l = s.split()
    a,s,b = l
    a,b = int(a),int(b)
    f = get_obj(s)
    print(f(a,b))

main()




